My dad was in an anti-aircraft artillery battery in WWII, and the first time that they encountered a Luftwaffe jet they knew that they a had a problem.
The electric motors that kept their guns locked on target weren’t fast enough to keep up with the jet. If they were going to shoot one down they were going to have to explode shells ahead of it and hope the jet ran into something.
Fortunately the Germans didn’t have enough jets for them to take advantage of their speed.
I read somewhere that the Birsmarck’s anti aircraft guns had problems with the British Swordfish torpedo bombers because they were so slow.